Power actuated snips or shears



C. A. DAWSON POWER ACTUATED SNIPS 0R SHEARS Jan. 7, 1958 Filed April 23,1957 3 Sheets-Sheet 1 INVENToR. CHARLES A. DAwsoN Agen Jan. 7, 1958 C.A. DAWSON POWER ACTUATED SNIPS OR SHEARS 3 Sheets-Sheet 2 Filed April25, 1957 INVENToR.

CHARLES A. DAWSON Agent Jan. 7, 1958 c. A. DAwsoN '2,818,643

POWER ACTUATED SNIPS OR SHEARS Filed April 25. 1957 3 Sheets-Sheet 5 TAT44 42 43 IN VEN Agent CHARLES A. DA N nite States atent rownn AcrUArnnsNrrs on snnans Charles A. Dawson, Pacoima, Calif., assignor to LockheedAircraft Corporation, Los Angeles, Calif.

Application April 2.3, 1957, Serial No. 654,605

Claims. (Cl. Sli- 228) This invention relates to power actuated orboosted hand tools, and relates more particularly to fluid pressureboosted or iiuid pressure actuated shears or snips for cutting andtrimming sheet metal and other sheet materials.

Hand shears are used extensively to cnt and trim sheet metal and in thefinal trimming operations the shears, as well as hand files, areresorted to to obtain the final accuracy. In the aircraft industry, andin other fields, thicker and harder sheet materials are being used to agreater extend and it is much more difficult to cut and trim such stockwith hand shears or snips. It is especially diiiicult to follow a linewith accuracy when cutting these thicker or harder sheets and much timeand effort is expended in obtaining the required results.

It is an object of the present invention to provide simple, practical,hand shears incorporating effective power booster means adapting theshears for the expeditious cutting 'of sheet materials. The powerbooster means of the invention relieves the operator of exertingphysical effort in the actual cutting of the stock, even thick, hardsheets, and therefore allows him to follow the cut or trim line withgreat accuracy.

Another object of the invention is to provide snips or shears of thiskind that are used and manipulated in the same manner as conventionalhand shears, being compact and relatively light in weight for easycontrol, direction and overall handling.

Another object of this invention is to provide snips or shears of thischaracter wherein the power means or booster mechanism has an actionclosely and accurately following and conforming to the actual motion oraction of the workmans hand so that the blades are operated andIcontrolled by the workman in the same fashion as the blades of typicalhand shears.

Another object of the invention is t-o provide power actuated shears ofthis character incorporating a feel means offering a mild resistance tomanual movement of the hand grip or handle so that the workman has asense of feel of the cutting action, which means also serves to reduceor prevent over-travel of the shears. The feel means is a springyieldingly urging both the thumb grip or handle and the control valve totheir norma-l or idle positions so that when the physical force beingexerted by the workman is relaxed or terminated the power operation andthe cutting action are simultaneously terminated. This spring alsooperates to yieldingly hold the valve closed and the handle in its idleposition when the tool is inactive.

A further object of this invention is to provide a power actuated orbooster hand tool of this kind in which the valving, porting, etc. arewithin or carried by the actuating piston which in turn is connectedwith the movable blade of the shears to operate the same.

Other objectives and features of the invention will become apparent fromthe following detailed description of a typical preferred embodimentillustrated in the drawings in which:

Figure 1 is a side elevation of the shears of the invention with thecylinder, a portion of the cylinder piston and associated partsappearing in vertical cross section;

Figure 2 is a top or plan view `of the tool;

Figure 3 is a front elevation of the tool with portions of the hand gripand handle broken away;

Figure 4 is an enlarged fragmentary vertical sectional view takensubstantially is indicated by line 4 4 on Figure 3; and

Figures 5 and 6 are enlarged fragmentary detailed sectional views takensubstantially as indicated by lines 5 5 and 6-6 respectively on Figure3.

The tool, as shown, includes a body 1G having a hand grip 11 on one endand a relative stationary blade 12 on its forward end. The major portionof the body 10 is in the nature of a cylinder having a fore and aftcylinder bore or opening 13. The grip 11 is adapted to receive thefingers of the workmans hand, as illustrated in Figure 1, and iscentrally positioned in a vertical plane at the rear end of the body 10.The relatively stationary blade 12 is carried on an arm 14 projectingforwardly from the body 10. The arm 14 is attached to the underside ofthe body by bolts 15, or the like, and may if desired be integral withthe blade 12. As shown in Figures l and 2, the blade 12 is spacedforwardly and slightly below the tool body to be conveniently engagedunder the work W. It is preferred to provide the tool body 10 with oneor more additional handles or grips to facilitate manual manipulation ofthe device. 1 have shown two horizontal sockets 16 projecting laterallyfrom the body 1d adjacent its forward end and a hand bar 17 adapted tobe removably screw-threaded in either socket, as desired. lt will beseen how the workman, by engaging one hand in the grip 11 and bygrasping the bar 17, may conveniently support and direct the tool.

The snips or shears embody a second or relatively movable active blade1S pivotally associated with the relatively stationary blade 12 by ahinge pin or screw 20. Th-e blades 12 and 18 are shaped and related tocoact in the manner of conventional shear blades and may preferably beprovided with hardened and ground active blade inserts or faces 21. Therelatively movable blade 1S has a lever arm 22 projecting upwardly withrespect to the hinge screw Ztl to have its upper end at or aligned withthe central longitudinal axis of the cylinder opening 13. As shown inFigure l, the blade 12 may engage under the work W with the blade 18above the work so that upon forward pivoting of the lever arm 22 theblades cooperate in cutting or shearing the work.

The power booster or power actuating means of the tool is operable toactuate or pivot the arm 22 of the relatively movable blade 18 under theprecise control of the workman or operator. The power actuating means isfluid pressure actuated and is preferably a pneumatically operatedcylinder and piste-n device comprising a piston 25 operable in thecylinder opening 13. The head of the piston 25 has an annular groovecontaining a seal ring 26 having sliding sealing engagement with thewall of the cylinder bore 13. The piston 25 is actuated or urgedrearwardly by a spring 2'7 arranged in the cylinder under compressionbetween the piston head and a cap or internal collar 2S threaded in theforward end of the cylinder opening. The piston 25 passes through thecollar 28 with considerable clearance, as shown at 29, and in thepreferred construction the seal ring 26 is an O ring or is otherwiseshaped to have line Contact with the wall of the cylinder opening 13.This arrangement allows the piston 2S to nd its own center `and to havelimited tilting or angular movement in the cylinder, the seal ring 26forming a fulcrum for such movement. The forward lower portion of thepiston 25 is notched or cut-away to leave a forwardly facing shoulder 31engageable with the collar to limit forward travel of the piston andthus prevent excessive compression of the spring 27. An operativeconnection is provided between the forward end of the piston 25 and thearm 22 of the movable blade 18. ln practice, this connection maycomprise a fork or yoke 32 having a stud 3? threaded in a centrallongitudinal bore 34 in the piston 25. The upper end of the blade arm2.2 is received in the yoke 32 and is operatively connected with theyoke by a pivot pin 35. It will be seen how fore and aft movement of thepiston 25 actuates and retracts the blade i3.

It is a feature that the porting and valvinfy for controlling operationof the piston 25 is carried in the piston itself. The air under pressurefor actuating the tool may be supplied by a flexible line or hose 36having an l. fitting 37 communicating with a port 3S in the forward endof the piston, see Figure 6. The port 3d extends tangentially to anaxial port or passage 39 which, in turn, is joined by a transversepassage dit. The passage d@ leads to the above mentioned axial bore oropening 3d. This bere 34, which has its forward end closed by the stud33 extends to the inner or rear end of the piston 2S to communicate withthe cylinder i3. A valve 42 is provided in the passage 39 to control theflow of actuating Huid pressure through the port or passage system justdescribed and to permit the exhausting of pressure from the cylinder 13and thus allow return or retrograde movement of the piston 25 by theaction of the spring 27. The valve 42 is arranged between and iscooperable with two spaced opposed valve seats d3 and 4d threaded orotherwise secured in the passage 39. The valve seat 4,3 faces forwardlyor toward the forward end of the piston 25 and the valve 42 has apointed or conical end cooperable therewith to close olf or prevent theflow of air under pressure through the passage system into the cylinder13. The valve seat 54 faces rearwardly and has a central bore or openingd5 leading from the passage 40 to the atmosphere. The valve d2 is shapedto cooperate with the seat 4d to close off the passage 45 and thusprevent the discharge of air pressure from the cylinder 13 to theatmosphere. A stem 46 on the valve 42 extends forwardly through thepassage d5 with considerable clearance to project from the forward endof the piston 25. As shown in Figures 4 and 5, the valve i2 isproportioned so that it leaves the passage 45 open when engaged on theseat 43. Conversely, when the valve 42 is urged against the seat by theaction of the actuating air pressure, and thus closes the passage d5,the air under pressure may iiow through the passages 33, 39, di) and 34into the cylinder lli. Furthermore, as seen in Figure 6, the valve l2may assume an intermediate position where it is spaced clear of bothseats S3 and 44.

The means for controlling or operating the valve 412 and thuscontrolling operation of the shear blade 19 includes a stem or rod 5dslidable longitudinally in a guide opening 5i in the upper portion ofthe tool body itl. A thumb grip 52 is provided on the rear end of therod 50 t0 receive the thumb of the workman, as illustrated in Figure 1.An L. shaped arm or plate 53 is attached to the forward end of the sliderod 5G to be spaced in front of the projecting piston 25. The rear faceof the plate S3 is engageable with the forward end of the valve stem 46.Spring means is provided to urge the plate 53 and rod 5t) rearwardly toactuate the valve 42 toward or against the seat 43 and to impart a senseof feel to the operators thumb engaged inthe grip 52. As shown in Figure5, a spring 54.- is arranged under compression between the front of theplate 53 and a washer 55 which bears against the head of a screw or stud56 on the piston 25. The stud 56 passes through an opening 57 in theplate 53 to lassist in guiding the plate and to prevent angular orrotary movement of the plate and slide rod Sil. The spring Sfiissufciently strong to resist the action of the actuating air underpressure and hold the valve 42 closed against the seat d3 and to returnthe valve to this posi- H tion when the workmans forward pressure isremoved from the grip 52. The workman of course may readily exertsufficient forward pressure on the grip 52 to move the rod Sti and plateforwardly against the action of the spring 542 to permit opening of thevalve i2 and thus allow actuating air under pressure to iiow into thecylinder i3 to actuate the blade 18. Since the spring 5dat all timesyieldingly resists forward movement of the grip 52 the workman sensesthe `action of the valve 42 and therefore the action of the shear bladei8.

It is believed that the operation of the tool will be readily understoodfrom the foregoing detailed description. Assuming that air underpressure is supplied to the hose or line 36 and assuming that the bladesl2 and 18 are in operative relation to the work W the operator orworkman merely engages his lingers through the handle l?. and his thumbthrough the grip 52 and actuates the grip and rod 5t) forwardly toproduce actuation of the shears. Upon such forward movement of the rod5t) the air under pressure in the passage 39 opens the valve Li2 to anextent proportional to the forward advance of the rod 5l) and plate 53and actuating air under pressure is admitted through the passages diland 34 to the cylinder f3. This actuates or moves the piston 25forwardly and causes the blade i8 to be actuated toward the relativelystationary blade 12 to cut the work W. It is to be particularly notedthat the extent of actuation of the blade i8 is determined solely by theextent of movement of the grip 52. Thus if the grip 52 is advanced onlya short distance the piston 25 is moved a proportionate distance by theabove described action until the valve 42 assumes a position spacedbetween the seats 43 and 44 so that the actuating air under pressureescapes through the port 45 at the same rate as it enters through. seat43. Under this condition the air pressure in the cylinder i3 merelybalances the action of the spring 27 allowing the piston 25 and blade ldto remain stationary. Thus since the valve 42 and the porting andpassage system are carried by the piston 2S itself there is a follow-upaction and balancing action which prevents over-travel of the blade iiiand assures that blade operation is accurately governable by movement ofthe operators grip 52. Following actuation of the blade 18 the operatormerely relaxes his forward pressure on the grip 52 and the spring 54moves the plate 5.3, rod Si) and grip 52 rearwardly. Such rear wardmovement allows the valve 42 to close against the seat 43 and to moveaway from the seat 44 so that the air under pressure in the cylinder 13is free to exhaust through the passage 45 to the atmosphere. This allowsthe spring 27 to return the pistou 25 to its initial position and toopen the blade 18, the plate 53 and rod 5@ returning rearwardly with thepiston. It is to be understood that the blade 18 may be operated, asabove described, to any intermediate or partially operated position andpartially returned, such actions being dependent entirely upon theworkmans movement and positioning of the grip 52. It is to be noted thatthe piston 25 provided with the single fulcrum seal ring 26 and freelypassing through the opening 29 may rock or tilt to a limited extent dueto the arcuate movement of the pivot pin 35 during actuation of theblade 18, avoiding any frictional or binding action.

Having described only typical forms of the invention I do not wish to belimited to the specific details herein set forth, but wish to reserve tomyself any variations or modifications that may appear to those skilledin the art and fall within the scope of the following claims.

I claim:

l. A tool of the character described comprising a cylinder, a pair ofcooperable cutting blades, one being relatively fixed the other beingpivoted, a piston operable in the cylinder and connected with thepivoted blade to actuate the same, a port system in the piston forreceiving actuating fluid pressure and having a passage leading to thecylinder and a passage leading to the atmosphere,

a valve in the piston passage system, the piston and valve beingrelatively movable between a first relative position where the valveprevents the flow of actuating pressure to the cylinder and puts thecylinder in communication with the passage leading to the atmosphere,and a second relative position where the valve permits the ow ofactuating pressure to the cylinder and closes said passage leading tothe atmosphere, and manually operable means for moving the valverelative to the piston to the second position and for restraining thevalve against movement when the piston moves said other blade toward theactive position.

2. A tool of the character described comprising a lcylinder, a pair ofcooperable cutting blades, one being relatively ixed the other beingpivoted, a piston operable in the cylinder and connected with thepivoted blade to actuate the same, means urging the piston and pivotedblade to inactive positions, a port system in the piston for receivingIactuating fluid pressure and having a passage leading to the cylinderand a passage leading to the atmosphere, a valve in the piston passagesystem, the piston and valve being relatively movable between a rstrelative position where the valve prevents the flow of actuatingpressure to the cylinder and puts the cylinder in communication with thepassage leading to the atmosphere, and a second relative position wherethe valve permits the flow of actutating pressure to the cylinder andcloses said passage leading to the atmosphere, a movable memberengageable with the valve and manually operable to allow the valve tomove relative to the piston to said second relative position so that thepiston is moved by the tluid pressure to actuate the pivoted blade, andmeans yieldingly urging the member toward the valve so that actuation ofthe blade is terminated when such movement of the piston brings thevalve into engagement with the member.

3. A tool of the character described comprising a pair of cooperableblades, one blade being pivoted relative to the other, actuating meansincluding two elements, one a cylinder, the other a piston, one elementbeing relatively stationary, the other being movable, an operativeconnection between the movable element and the pivoted blade whereby thelatter is operable by the former, :a system of communicating passages inthe movable element including an inlet passage receiving actuatingfluid'v pressure, a cylinder passage leading to the cylinder and anexhaust port, a valve in said system movable relative to the movableelement between a iirst position where it closes said inlet passage andthe exhaust port is open and a second position where it closes theexhaust port and the inlet passage is open to the cylinder passage, and.a manually movable member cooperable with the valve to hold it in saidfirst position and movable to allow the valve to assume the secondposition until resulting movement of the movable element by the pressureadmitted to the cylinder brings the valve to said iirst relativeposition to terminate such movement of the movable element.

4. A tool of the character described comprising a pair of cooperableblades, one blade being pivoted relative to the other, actuating meansincluding two elements, one a cylinder, the other a piston, one elementbeing relatively stationary, the other being movable, an operativeconnection between the movable element and the pivoted blade whereby thelater is operable by the former, a system of communicating passages inthe movable ele- -ment including an inlet passage receiving actuatinguid pressure, a cylinder passage leading to the cylinder and an exhaustport, a valve in said system movable relative to the movable elementbetween a first position where it closes said inlet passage and theexhaust port is open and a second position where it closes the exhaustport and the inlet passage is open to the cylinder passage, a manuallymovable member cooperable with the valve to hold it in said firstposition and movable to allow the valve to assume the second positionuntil resulting movement of the movable element by the pressure admittedto the cylinder brings the valve to said rst relative position toterminate such movement of the movable element, and means reactingbetween the movable element and said member yieldingly resistingmovement of the member and movement of the valve from said position.

5. A tool of the character described comprising a body, a hand grip onthe body, a pair of cooperable blades carried by the body, one bladebeing pivoted relative to the other, actuating means including twoelements, one a cylinder, the other a piston, one element beingrelatively stationary, the other being movable, an operative connectionbetween the movable element and the pivoted blade whereby the latter isoperable by the former, a system of communicating passages in themovable element including an inlet passage receiving actuating uidpressure, a cylinder passage leading to the cylinder and an exhaustport, a valve in said system movable relative to the movable elementbetween a first position where it closes said inlet passage and theexhaust port is open and a second position where it closes the exhaustport and the inlet passage is open to the cylinder passage, a movablemember carried by the body and engageable with the valve to hold it insaid rst position, a thumb grip on the member whereby the operator maymove the member to vallow movement of the valve to the second positionby the tiuid pressure in the inlet passage, and spring means resistingsuch movement of the member so as to normally hold the valve in saidfirst position.

6. A tool of the character described comprising a body, a hand grip onthe body, a pair of cooperable blades carried by the body, one bladebeing pivoted relative to the other, actuating means including twoelements, one a cylinder, the other a piston, one element beingrelatively stationary, the other being movable, an operative connectionbetween the movable element and the pivoted blade whereby the latter isoperable by the former, a system of communicating passages in themovable element including an inlet passage receiving actuating uidpressure, a cylinder passage leading to the cylinder and an exhaustport, a valve in said system movable relative to the movable elementbetween a irst position where it closes said inlet passage and theexhaust port is open and a second position where it closes the exhaustport and the inlet passage is open to the cylinder passage, a springyieldingly urging the elements to the relative positions where thepivoted blade is in the inactive position, a movable member carried bythe body and engageable with the valve to hold it in said firstposition, a thumb grip on the member whereby the operator may move themember to allow movement of the valve to the second position by thefluid pressure in the inlet passage, and spring means resisting suchmovement of the member so as to normally hold the valve in said rstposition.

7. A tool of the character described comprising a body, a pair ofcooperable blades carried by the body, one blade being pivoted relativeto the other, actuating means including two elements, one a cylinder,the other a piston, one element being relatively stationary, the otherbeing movable, an operative connection between the movable element andthe pivoted blade whereby the latter is operable by the former, a springurging the elements to the relative positions where the pivoted blade isin the inactive position, a system of communicating passages in themovable element including an inlet passage receiving actuating uidpressure, a cylinder passage leading to the cylinder and an exhaustport, a rst valve seat in the inlet passage, a second valve seat in theexhaust port, the seats being in spaced opposed relation, a valvearranged between the seats, the movable element and valve being relatedfor relative movement so that the valve may assume a iirst relativeposition where it engages the tirst seat so that the spring holds thepivoted blade in the inactive position and a second position where itengages the second seat to admit actuating pressure to the cylinder toactuate the pivoted blade, and a member manually movable on the bodyengaging the valve to hold it in the lirst position and movable to allowthe valve to be moved to the second position by the fluid pressure.

8. A tool of the character described comprising a body, a pair ofcooperable blades carried by the body, one blade being pivoted relativeto the other, actuating means on the body including two elements, one acylinder the other a piston, one element being relatively stationary,the other being movable, an operative connection between the movableelement and the pivoted blade whereby the latter is operable by theformer, a spring urging the elements to the relative positions where thepivoted blade is in the inactive position, a system of communicatingpassages in the movable element including an inlet passage receivingactuating iluid pressure, a cylinder passage leading to the cylinder andan exhaust port, a first valve seat in the inlet passage, a second valveseat in the exhaust port, the seats being in spaced opposed relation, avalve arranged between the seats, the movable element and valve beingrelated for relative movement so that the valve may assume a :'irstrelative position where it engages the iirst seat so that the springholds the pivoted blade in the inactive position and a second positionwhere it engages the second seat to admit actuating pressure to thecylinder to actuate the pivoted blade, a stem on the valve projectingaxially from an end of the movable element, and a manually movablemember on the body engaging the stem to hold the valve in the iirstposition and movable axially outward to allow the valve to move to thesecond position.

9. A tool of the character described comprising a body, a pair ofcooperable blades carried by the body, one blade being pivoted relativeto the other, actuating means on the body including two elements, one acylinder, the other a piston, one element being relatively stationary,the other being movable, an operative connection between the movableelement and the pivoted blade whereby the latter is operable by theformer, a spring urging the elements to the relative positions where thepivoted blade is in the inactive position, a system of communicatingpassages in the movable element including an inlet passage receivingactuating fluid pressure, a cylinder passage leading to the cylinder andan exhaust port, a iirst valve seat in the inlet passage, a second valveseat in the exhaust port, the seats being in spaced opposed relation, avalve arranged between the seats, the movable element and valve beingrelated for relative movement whereby the valve may assume a firstrelative position where it engages the irst seat so that the springholds the pivoted blade in the inactive position and a second positionwhere it engages the second seat to admit actuating pressure to thecylinder to actuate the pivoted blade, a stem on the valve projectingaxially from an end of the movable element, and a manually movablemember on the body engaging the stem to hold the valve in the rstposition and movable axially outward to allow the valve to move to thesecond position, and a spring reacting between the movable element andthe member urging the latter against the stem to hold the valve in thefirst position.

l0. A tool of the character described comprising a pair of cooperableblades, one blade being pivoted relative to the other, actuating meansincluding two elements, one a cylinder, the other a piston, one elementbeing relatively stationary, the other being movable, an operativeconnection between the movable element and the pivoted blade whereby thelatter is operable by the former, a system of `communicating passages inthe movable element including an inlet passage receiving actuating fluidpressure, a cylinder passage leading to the cylinder and an exhaustport, a valve in said system movable relative to the movable elementbetween a rst position where it closes said inlet passage and theexhaust port is open and a second position where it closes the exhaustport and the inlet passage is open to the cylinder passage, a manuallymovable member cooperable with the valve to hold it in said firstposition and movable to allow the valve to assume the second positionuntil resulting movement of the movable element by the pressure admittedto the cylinder brings the valve to said first relative position toterminate such movement of the movable element, and means reactingbetween the movable element and said member yieldingly resistingmovement of the member and movement of the valve from said tirstposition, the valve being shaped and proportioned so as to assume aposition intermediate said first `and second positions to allow flowthrough the inlet passage and the exhaust port and thereby maintain thepivoted blade in an intermediate position when movement of the movableelement closes with the pivoted blade in a desired position.

No references cited.

